Avalanche Advisory

Turnagain Area Avalanche Advisory

Thursday, March 3rd 2016 5:36 am by Heather Thamm

ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.

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The Bottom Line

The avalanche danger is MODERATE today in Turnagain Pass for cornice fall, lingering wind slabs, and glide avalanches. Triggering a large cornice or an old wind slab 1-2’ is possible today and will become more of a concern throughout the day as the sun adds stress to solar aspects. Glide cracks continue to open up and move and can release spontaneously without warning. Evaluate the terrain for any of these issues and pay close attention to how the sun is affecting the surface snow on sunny aspects.

*Yesterday we received word of a large natural avalanche South of Grandview along the railroad corridor. Observations over the last few weeks have identified several buried weak layers within the snowpack in the Summit Lake area. No information is known about the structure of this particular avalanche, but is something to keep in mind if venturing into Lynx Creek or the Summit Lake zone.

Show the Complete North American Avalanche Danger Scale

North American Public Avalanche Danger Scale

Avalanche danger is determined by the likelihood, size and distribution of avalanches.

Danger Level

Travel Advice

Likelihood of Avalanches

Avalanche Size and Distribution

5 Extreme

Avoid all avalanche terrain.

Natural and human- triggered avalanches certain.

Large to very large avalanches in many areas.

4 High

Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

Natural avalanches likely; human- triggered avalanches very likely.

Large avalanches in many areas; or very large avalanches in specific areas.

Due minimal snow coverage and signs of snow machine impact to exposed vegetation the Primrose Trail access to Lost Lake has officially closed today, March 3, 2016. Thanks to many of you who have made an effort to stay on the trail and to educate others about the consequences of tearing up the vegetation. Until this area recieves more snow the trail will remain closed.

Avalanche Problem 1

Cornice fall may be one of the larger hazards today with sunshine acting to weaken these already tenuous bombs. Cornices right now are LARGE and UNPREDICTABLE- some bigger than semi-trucks and some with large cracks extending their full length. Yesterday melting snow and dripping water could be seen on cornice faces during the heat of the day along Magnum Ridge. Today the sun will continue to weaken cornices making human triggered (snowmachine or skier) and natural cornice fall more likely in the afternoon. Limiting time spent under these is key and giving them extra room along ridgelines will be necessary. Not only would it suck to trigger a cornice while on top of one, imagine what it would be like if people were also below it. Evaluate all ridgelines and slopes for potential cornice fall and be weary of existing skin tracks and up-routes. There are many areas where the “normal” route is in the line of fire.

Magnum Ridge Cornice - The estabilshed skin track is directly on top of 30-40' cornice feature.

Same corniced ridge on Magnum. Note the long crack observed on February 18th before a 10 day storm added more weight and stress to this cornice. Photo by Amanda Goss.

Avalanche Problem 2

Strong winds during a 10-day storm have created layers of wind-affected snow throughout Turnagain Pass. Observations over the last several days have been showing this problem to be stabilizing, however today’s warm temperatures and direct sun could be a catalyst for a human triggered wind slab. Triggering a wind slab is still possible on slopes steeper than 35 degrees especially on slopes with unsupported terrain features. Ease into steeper terrain with caution and avoid solar aspects if you find moist surface snow or see wet loose point releases in motion.

Additional Concern

Glide cracks are moving and coming out of hiding after they were covered by wind and snow during the storm cycle. Although it has been several days since the last glide crack we know of released and avalanched, they are still on the move. Limiting time spent under cracks is crucial, as they will mow anything down in their path if one does release.

Very large glide crack on the SW shoulder of Cornbiscuit - view from the Seward Hwy. The entire SW face of Cornbiscuit has extensive glide cracks. Click HERE for more pictures from yesterday.

Mountain Weather

Yesterday skies were clear and sunny and temperatures reached mid-high 30’s F during the warmest part of the day, around 2pm. Calm winds switched directions mid day from an Easterly direction to a Westerly direction. Overnight skies remained clear and temperatures dropped into the teens to mid 20’s F.

Today Westerly winds are expected in increase slightly 10-15mph along ridgetops. Skies will remain sunny and day time temperatures are expected to spike mid day.

Tomorrow a pattern shift is expected with a possibility of scattered snow showers.

PRECIPITATION 24-hour data (6am - 6am)

Temp Avg (F)

Snow (in)

Water (in)

Snow Depth (in)

Center Ridge (1880')

27

0

0

140

Summit Lake (1400')

22

0

0

42

Alyeska Mid (1700')

28

0

0

105

RIDGETOP 24-hour data (6am - 6am)

Temp Avg (F)

Wind Dir

Wind Avg (mph)

Wind Gust (mph)

Sunburst (3812')

28

NE becoming W

4

10

Seattle Ridge(2400')

24

n/a

n/a

n/a

This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).

Riding status is not associated with avalanche danger. An area will be open to motorized use in accordance to the Forest Management Plan when snow coverage is adequate to protect underlying vegetation. Backcountry hazards including avalanche hazard are always present regardless of the open status of motorized use areas.

(Updated: Dec 18, 2018 )

AREA

STATUS

WEATHER AND RIDING CONDITIONS

Glacier District

Johnson Pass:

Open

Please stay on trail to avoid resource damage through Forested areas.

Placer River:

Closed

Closed

Skookum Drainage:

Closed

Closed

Turnagain Pass:

Closed

Closed November 21 due to inadequate snow conditions. #hopeforsnow

Twentymile:

Closed

Closed

Seward District

Carter Lake:

Open

Lost Lake Trail:

Open

Please stay on trail to avoid resource damage through Forested areas.

Primrose Trail:

Open

Please stay on trail to avoid resource damage through Forested areas.

Resurrection Pass Trail:

Closed

Closed for the 2018/19 season. Next season will be open to motorized use.

The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.
This advisory provided by the Chugach National Forest, in partnership with Friends of the Chugach National Forest Avalanche Information Center.